1. Field of the Invention
The present invention relates generally to an apparatus and method for securing cables, wires conduits, and junction boxes within a wall cavity and more particularly junction boxes for terminating electrical circuits on the surfaces of walls, floors, ceilings, or equipment enclosures for both high and low voltage circuits.
2. Background
Electrical junction boxes, also sometimes referred to as outlet boxes, have been used since the advent of electricity in high voltage circuit applications and later with the advent of the telephone in low voltage applications. These boxes are generally mounted with the front side of the box positioned flush with the installed wall covering material and include fittings for attaching a wall plate, switches, plugs, connectors, and electrical/electronic devices to the box. The box also provides a means for connection of cables and conduits within the box or termination of cables to apparatus mounted within the box.
The use and design of junction boxes has progressed as technology has changed and as new applications were needed. With these advances, several products became available that solved each application related problem individually while requiring, in some cases, a multitude of boxes. With these varying designs many problems persist, and limited use of special features precludes production of the units in high volume thereby increasing manufacturing and end-user costs. Further, these and other problems persist resulting in unwieldy inventories for manufacturers, distributors, suppliers and installers alike. In addition, the units provided for sale often lack the most efficient design due to an attempt to provide a product, which has a more general application but, in many cases, doesn't solve any particular application well. For example, current boxes each must be mounted in a particular way due to their uni-functional design that requires the box be oriented a particular way to allow the mounting features to be effective.
Low voltage cables tend to be more fragile than high voltage cables. Because of on-going technology advancements and the need to increase bandwidth capacity of low voltage cables, low voltage cables are becoming even more fragile than previous cables. In order to prevent loss of bandwidth capacity, kinking or excessive bending of these cables should be avoided. When installing low voltage circuits, the current practice is for installers to cut the back off a standard high voltage electrical junction box. The new opening allows the necessary bending radii for the low voltage cables and, also, allows the mounting of low voltage apparatus, which often fills all of the space inside the junction box. The edges of standard electrical junction boxes can damage fragile cables when they are pulled through the openings. Installers usually do not have enough room inside standard junction boxes to coil multiple cables during the wall installation phase of construction. The aforementioned installation approach does not provide adequate protection or a neat method for holding the cables in place. Consequently, the cables stored in such a cramped, unorganized fashion are subject to damage after they are installed prior to completion of the construction phase. Further, the current practice does not provide a convenient way to secure an extra long service loop, which would allow easy connection of very small, intricate terminating devices.
High voltage cables commonly used for 120-volt outlets and lighting circuits range from two #14 conductors with a ground wire to three #12 conductors with a ground wire. As a result, the cable diameter between the two extremes can vary by as much as three times in size. Junction boxes are used to connect the circuits and mount electrical terminating devices such as outlets, switches and lighting fixtures. To facilitate these circuits, multiple openings for the cables to enter the box are required and because of limited space within the box, each opening is sized to accommodate both cable size extremes.
Methods for securing these cables within the junction box are determined by the National Electric Code (NEC). The NEC requires high voltage cables to be anchored no greater than four inches from junction boxes without a cable-securing device and 8 inches when a cable-securing device is provided. In applying these codes, multiple gang and wall boards mounted junction boxes would normally require a cable-securing device to anchor the cable would be more than 4 inches away, whereas a single junction box mounted to a framing structure is within four inches. Underwriting Laboratory (UL) certification testing for the securing device is also required. The UL test for the securing device requires the cable entering the bottom of the box to be subjected to a direct vertical pull of 25 pounds for 5 minutes in a conditioned environment of minus 20 degrees centigrade without damage to the cable sheath or conductors and a displacement of the cable of more than ⅛ inch.
Although high voltage cables tend to be more robust than low voltage cable because of the cable sheaths and wire insulation used, they can be subjected to damage when placed in the junction box. The current art available either provides no anchoring devices with an opening sized for the largest cables or provides inadequate clamping designs. The clamping designs either provide insufficient clamping of the smaller cables or provide too much clamping for the larger cables potentially damaging the cable and making it difficult pulling any size cable into the box difficult.
As a result of these and other problems there is a need for a universal junction box that includes a cable-securing device with the capability to handle both low voltage and high voltage cable in a safe and effective manner. A universal junction box is needed that can be easily mounted in a multitude of environments and orientations and reduces wall clutter while making efficient use of the available wall space. The universal junction box of the present invention increases the ease of installation by allowing easy mounting in many places and provides sufficient anchoring of all sizes of cables and commonly used flexible conduits while not causing damage to any of them. This invention reduces costs while producing installation efficiencies and reducing junction box inventories.